A service is defined as being a pre-defined sequence of actions such as for example, recording data, reading the global time of the platform, reading a land map in a database, etc.
This sequence is carried out by a specific service provider allowing the carrying out of the sequence of actions by a set of software and/or hardware units. A service is accessible from one or several subscribed client applications via the distributed hierarchical architecture of multiple accesses to services.
When the service provider ends the service or a portion of the service (depending on the type of service) requested by the client application(s), the service provider either sends «or not» a result to the calling client application(s).
In the state of the art, thus, for example, systems based on the present integrated modular avionics concept (IMA for «Integrated Modular Avionics») (conventional) apply one or several services supporting one or several avionic applications (a very limited number) without applying communication resources between this(these) service(s) and the corresponding applications since this(these) service(s) is(are) only local to a physical module.
Access to the local service is accomplished via a programming interface (API for «Application Programming Interface») for only the application(s) hosted on the same physical module as the service.
The communication between applications within different physical modules is generally ensured by a computer avionic communications network connecting the corresponding modules.
The communication between applications is managed by using space and time partitioning properties of the data, allowing independent and deterministic processing operations and exchanges.
Such management is respectively based on the ARINC 653 and ARINC 664 standards.
The avionic applications are based on a model of exchanges of the «Publisher/Subscriber» type. These applications have access to a set of services only based on the ARINC 653 standard resorting to dedicated services localized on the same physical module as the applications.